Toolholder for lathes



Feb. 18, 1941. w. L. GROENE 2,232,323

TOOLHOLDER FOR LATHES Filed May 8, 1959 DIRECTIO .1 OF TooL 1 FEED INVENTOR.

w IT N E 55.

Patented Feb. 18, 1941 UNITED STATES TOOLHOLDER FOR LATHES Willard L. Groene, Cincinnati, Ohio, assignor to The R. K. LeBlond Machine 'Tool Company, Cincinnati, Ohio, a corporation of Delaware Application May a, 1939, Serial No. 272,430

11 Claims.

My invention pertains to toolholders for lathes, and more particularly to toolholders for lathes such as are used for turning the bearings of automobile engine lcranksha-fts and for similar work. The improvement pertains to that type of lathe toolholders in which a turning tool is mounted in operative relation to an opposing roller or land, to prevent the work piece from being sprung out of shape by the thrust of the tool as it is'f-ed radially of the axis of the work piece, the tool of such toolholders having tangential floating movement substantially perpendicular to said direction of radial feeding. Toolholders of this type are shown, for example, in Patents 2,089,421 dated August 10, 1937, and 2,154,739 dated April 18, 1939.

More specifically this invention pertains to certain specific improvements in the mounting of the toolholder for effecting the tangential floating movement of the cutting edge of the cutting tool substantially perpendicular to the line of feeding of the tool radially of the work, the broad principles of this arrangement being fully set forth and described in the Patent 2,089,421dat-ed August 10, 1937, the object of this invention being the substitution of a sliding mounting instead of a pivotal mounting for effecting said tangential floating movement of the tool.

It is customary in structures of this character to mount the tool and the roller of land in a solid head, block, or toolholder, and this block is so mounted on the frame of the lathe as to be capable of a limited free oscillatory or floating movement that permits the cutting point of the tool to move along an imaginary line drawn tangent to the circle of the revolving work piece at the point of cut. Such floating movement of the tool has heretofore been made possible by mounting the tool block on a journal bearing parallel with the axis of the Work piece and located at a point on the lathe frame sufliciently remote from the axis of the work to permit the tool to have the required amount of -moveme'nt.

Difdculties have developed in practice 'fromthe use of such floating pivoted tool-holders; One of these difficulties has arisen from the fact that the remote .pivoted bearing has necessarily been a short bearing which will permit a slight,- but very undesirable sidewise movement of the edge of the cutting tool after long use. In the turning of line bearings for high speed engines variations of even a few thousandths of an inch from perfect accuracy are not desirable; hence great importance must be attached to keeping the cutting edge of the tool perfectly parallelwith the PATENT OFFICE imaginary line which is the axis of rotation of the work piece. When a tool is employed whose width is equal to the length of the bearing to be turned, it has happened that the side edges of the tool, in cutting their way in between the two 5 webs of a crank-shaft, were subjected to unequal sidewise thrust. Consequently, if there was only a slight sidewise movement of the toolholder as a result of such thrust, imperfect work would result. 7

The journal pin type of mounting for such a toolholder has been found lacking in that degree of stability which is required in the present day development of the internal combustion engine art.

It is an object of my invention, therefore, to overcome this and other difliculties inherent in earlier toolholder mountings, and to provide a stronger, more reliable, simpler, and less expensive toolholder construction.

My improvement, therefore, aims to eliminate the pivoted mounting for a'floating toolholder, and to attain the improved results by mounting it-on the frame of a lathe, not by means of a .pivot which necessarily has restricted bearing area and consequently a tendency to permit slight sidewise movement or rocking of the tool away from true parallelism with the axis of the work piece, but, by means of .a long guideway of ample bearing area that extends a considerable distance above and below the horizontal center lined the tool, to afford ample rigidity against any tendency of the tool to be sprung from its true tangent cutting line on the surface of the work piece, yet permitting the necessary slight amount of movement of the cutting edge parallel to the axis of the rotating piece.

- In' connection-with such a positively guided andslidably mounted toolholder I provide means for. adjusting the tool and the toolholder with 40 respect to the carriage in which the toolholder is mounted so that the cutting edge of the tool will travel into the work the precise amount required to reduce the Work to size.

' -In the drawing: Figure I- is an enlarged elevation'of the tool holder-as viewed axially of the work piece. As

here illustrated, the toolholder is shown applied 1 to machining a crank pin of a crankshaft.

Figure II is a section through the sliding mounting of the toolholder on the line II-II ,of Figure I. v

Figure III is a View of the toolholder and workpiece as seen from a position perpendicular to the axis of the work piece. 1

The toolholder 6 has a sliding mounting 1 on the tool carrying frame 2 comprising the nicely fitting dovetailed surfaces 3, 4, and 5, best shown in Figure II, said sliding mounting being so arranged on the tool carrier 2 as to effect tangential floating movement of the cutting edge 32 of the cutting tool 20 in a line 35 which is substantially perpendicular to the lines of tool feeding A or D. The toolholder, thus freely mounted for sliding movement on the mounting 1, has a roller 8 carried on a stud 9 in the bifurcated portion 9a.

A plunger i0, slidingly fitted in a suitable hole I l in the tool carrying frame 2, is urged outwardly by a spring held in contact with the surface 6a of the toolholder 6, the purpose of this arrangement being constantly to urge the member 6 with its roller 8 toward the work piece and to hold the roller 8 in contact to prevent the spring plunger I0 from moving the member 6 too far toward the work W, when the roller is retracted from the work piece at the starting position of the cutting tool, a stop is provided comprising a bar l3 bolted by means of the screw M to the tool carrier 2, which coacts with the surface 6b of the tool holder 6.

Secured to the toolholder 6 by suitable studs "and nuts I8 is a tool block I9 carrying the usual vertical form tool 20. A tongue 2|, formed integral with the tool block l9, fits slidingly in a slot 22 inthe member 6 so that the block I9 may be moved substantially radially of the axis of the work piece W. Elongated holes 23 are provided in the block l9 so that the block may be adjusted when the nuts I3 on studs H are loosened. A-back-up screw 28, fitted in a tapped hole 23 in a back-up block 30 fixed in the tool block l9, provides means for adjusting the tool 20 in the dovetail guides 3| provided in block l9.

As is indicated in Figure I toolholder 6 is capable of limited movement so that the cutting edge 32 of the tool 29 may have a slight movement along an imaginary line 35 tangent to the circle of the work piece at the point of cutting 32. It is to be noted that when properly adjusted the tool point 32 should be on the straight line path of feeding AA or the arcuate path of feeding DD which path is through the center 33 of the work surface being turned and the cutting edge 32 of the tool and substantially perpendicular to the line of movement of the guideway I so that the angle F be substantially By this arrangement the tool is adapted to move in the imaginary line 35 tangent to the work piece at the normal cutting position 32 of the tool point. It can be seen that when the tool moves in the line 35 a relatively small amount either side of the line AA or DD practically no change will result in the distance of the tool point 32 from the center 33 of the work being turned, which relationship determines the diameter of the crank pin P and its position relative to the main axis of rotation 36 of the work crankshaft W.

The roller 8 bears against the work piece at a point 31 which of necessity is on the line BB passing through center 33 of the crank pin P and the center 38 of the roller pin 9. Preferably the angle C between the lines AA and BB should be substantially 90 depending upon the diameter of the work surface being finished and the characteristics of the material. The cutting angles of the faces 39 and 40 of the tool 20 will likewise vary according to the nature of the work piece.

After the tool 20 has been properly adjusted the relationship of the points 32, 33 and the angle C all remain fixed relative to each other during the machining operation. Cutting action and reduction in diameter of the work piece is accomplished by causing relative movement between the tool and work piece along the line AA as in the case of machine wherein the relative movement is in a straight line as illustrated in Figure 2 of Patent 2,089,421 or along the arcuate path D-D which passes through the point 3 Zand 33 as in the case of the machine having arcuate relative movement as illustrated in Figures III and IV of said Patent 2,089,421. Obviously the sliding mounting l is arranged for movement substantially perpendicular to the line of relative feeding passing through points 32 and 33 in order to effect the tangential movement of the cutting edge 32 of the tool 20 in the line 35 perpendicular to said line of relative feeding. Thus the angle G should be substantially 90.

In machining an eccentric portion of a work piece, as for example, the crank pin P of the work crank W in Figure I, the centers 33 of which describe an orbital path E about the main axis 36 of the crankshaft, it is necessary to cause some point, for example point 34 of the toolholder 6 to follow an exact orbital path F of the diameter equal to that of the orbital path E described by the axis 33 of the crank pin P. The point 34 on the work holder will then describe the circle F about an imaginary center 4|, with center 4| as equivalent to the center or main axis of rotation 36 of the work crankshaft W.

This toolholder is applicable tomac-hines having arcuate or straight line feeding movements as illustrated inthe Patent 2,089,421 cited above, which lathes are for orbital turning of the crank pins of crankshafts. It is also to be clearly noted that this invention is adapted to lathes not of an orbital character wherein the relative feeding of the tool and workpiece is produced either along a straight line path of travel AA or arcuate path of travel DD. This invention is especially well adapted to lathes having a multiplicity of work spindles.

Having now set forththe nature of my invention and illustrative of examples of adaptation of this invention, what I claim is:

- 1. In a lathe, a rotatable work holder, a slidably mounted toolholder, the direction of sliding movement being arranged in a plane substantially perpendicular to a plane passing through the axis of the work holder and the cutting edge of a cutting tool in said toolholder, said toolholder contacting a work piece in said work holder, and means for feeding the cutting edge of said tool in said second mentioned plane radially of the axis of said work holder.

2. In a lathe, a rotatable work holder, a slidably mounted toolholder, the direction of sliding movement being arranged in a plane substantiallyperpendicular to 'a plane passing through the axis of the work holder and the cutting edge of a cutting tool in said toolholder, said tool- .holder contacting a work piece in .said work holding movement being arranged in a plane substantially perpendicular to a plane passing through the axis of the work holder and the cutting edge of a cutting tool in said toolholder, said toolholder contacting a work piece in said work holder, resilient means for maintaining said contact, a stop limiting the movement effected by said resilient means, and means for causing relative feeding between said tool and the work holder.

4. In a lathe, a rotatable work holder, a slidably mounted toolholder, the direction of sliding movement being arranged in a plane substantially perpendicular to a plane passing through the axis of the work holder and the cutting edge of a cutting tool in said toolholder, said toolholder contacting a work piece in said work holder, resilient means for maintaining said contact, means for moving said toolholder so as toconform the tool to an eccentric portion of the work piece, and means for causing relative feeding between said tool and work piece.

5. In an orbital lathe, a rotatable work holder, a slidably mounted toolholder, the direction of sliding movement being arranged in a plane substantially perpendicular to a plane passing through the axis of the eccentric portion being turned on a work piece in said work holder and the cutting edge of a cutting tool in said toolholder, said toolholder contacting said work piece, and means for feeding the cutting edge of said tool in said second mentioned plane radially of the axis of said eccentric portion being turned.

6. In an orbital lathe, a rotatable work holder, a slidably mounted toolholder, the direction of sliding movement being arranged in a plane substantially perpendicular to a plane passing through the axis of the eccentric portion being turned on a work piece in said work holder and the cutting edge of a cutting tool in said toolholder, said toolholder contacting said work piece, resilient means for maintaining said contact, and means for causing relative feeding between said tool and the work piece in said work holder.

'7. In an orbital lathe, a rotatable work holder, a slidably mounted toolholder, the direction of sliding movement being arranged in a plane substantially perpendicular to a plane passing through the axis of the eccentric portion bein turned on a work piece in said work holder and the cutting edge of a cutting tool in said toolholder, said toolholder contacting said work piece, resilient means for maintaining said contact, a stop limiting the movement effected by said resilient means, and means for causing relative feeding between said tool and the work hold- 8. In a lathe for orbital turning, a toolholder, means independent of the work piece being turned for causing said toolholder as a whole to move in an orbital path following the work, and means for resting said toolholder on the work so that said work may cause sliding movements of said toolholder while said toolholder as a whole follows said orbital path.

9. In a lathe for orbital turning, a toolholder, a tool in the toolholder, means independent of the work piece being turned for causing said toolholder as a whole to move in an orbital path following the work, a sliding mounting means for the toolholder permitting the cutting edge of said toolholder to move in a straight line tangent to the work surface being machined while said toolholder as a whole follows said orbital path.

10. In a lathe, for orbital turning, a toolholder, a tool in the toolholder, means independent of the work piece being turned for causing said toolholder as a whole to move in an orbital path following the work, a sliding mounting means for the toolholder permitting the cutting edge of said toolholder to move in a straight line tangent to the work surface being machined and means dependent upon the work piece to control said sliding movement while said toolholder as a whole follows said orbital path.

11. In a lathe for orbital turning, a toolholder, a tool in the toolholder, means independent of the work piece being turned for causing said toolholder as a whole to move in an orbital path following the work, and a means dependent upon the work piece to move the cutting edge of said tool in a straight line tangentially of the work surface being machined while said toolholder as a whole follows said orbital path.

WILLARD L. GROENE. 

